The present invention relates to an improved fabric antenna, especially an antenna for incorporation into a garment.
It is known to provide an antenna in a garment, for example for use in a mobile telecommunications system. One example of this is given in EP-A-0 637 094 to Matsushita which describes an antenna comprising metal antenna elements in the form of conductive plates formed on opposite sides of a dielectric slab; the antenna is intended for mounting on a human shoulder, and the rigidity of the dielectric slab prevents deformation of the antenna. However, the rigidity also results in the antenna being uncomfortable and inconvenient to wear.
It is also known to provide an antenna in the form of an at least partially fabric construction. In U.S. Pat. No. 5,771,027, the conducting fabric for an antenna comprises a grid of electrical conductors woven into the warp of a resin reinforced cloth forming one layer of a multi-layer laminate structure, particularly a polarizing grid integrated into the laminated structure of a reflector of a light-weight parabolic antenna, but such an antenna is not suitable for telecommunications use. This unsuitability is to a certain extent down to the generally bulky size and configuration of a parabolic antenna, but also due to its unsuitability in situations where there is a requirement for an antenna with an omni-directional capability.
Accordingly, it is an object of the present invention is to provide a fabric antenna capable of unobtrusive incorporation into a garment and suitable for mobile telecommunications use.
According to the invention there is provided an antenna for mobile telecommunications use characterised by first and second spaced layers of electrically conducting fabric; a layer of electrically insulating fabric between the first and second layers; first connection means by which electrical contact is made between the first and second layers; and second connection means by which the first and second layers are connectable to telecommunications equipment.
In one embodiment, the antenna is incorporated into a shoulder portion of a garment, for example as a shoulder pad. In another embodiment the antenna is incorporated into a lapel of a garment. In both embodiments it is highly preferable that the layer of electrically conducting fabric adjacent a wearer of the garment is of substantially greater area than the other layer of electrically conducting fabric and is connected as a ground plane so that the user is isolated from the strongest electrical fields emitted by the antenna.
In a preferred arrangement the antenna comprises a single piece of electrically conducting fabric folded around the insulating fabric, whereby the fold in the conducting fabric constitutes the first connection means.
By use of the invention as the antenna in mobile telecommunications equipment, the remainder of the handset can be made smaller and lighter than was previously possible through separation of the component parts, particularly as the overall size of many mobile telephone handsets is constrained by the size of the antenna assembly used. Such an antenna is flexible and lightweight and does not impede the movements of the user. The mobile telecommunications equipment may be a mobile telephone or a pager or a wireless Local Area Network (LAN).